1. Field of the Invention
The present invention relates to an image processing apparatus and a digital signal processing method.
2. Discussion of the Background
An image data processing operation for an image processing system, such as a digital photocopier or a multi-functional image processing apparatus which performs, for example, an image scanning function, a facsimile function, a photocopying function, and a printer function, is generally practiced by a hard-wired logic circuit. On the other hand, an attempt to process image data using a digital signal processor in place of the hard-wired logic circuit is known. As an example, a digital signal processor structured with a so-called “single instruction stream multiple data stream architecture” (SIMD) architecture is known as powerful enough to perform a real-time image data processing in a digital photocopier. A digital signal processor structured with the SIMD architecture has plural signal processors and each of the plural signal processors simultaneously executes the same instruction for different data. Thus, the digital signal processor structured with the SIMD architecture achieves a high throughput of an image processing operation.
In the above-described multi-functional image processing apparatus, because of the diversity of image processing operations, a total program code for a digital signal processor, which can be structured with plural sets of program modules for plural image processing functions, becomes relatively large in size. On the other hand, a capacity of a program-storing device provided inside a digital signal processor may not be large enough for storing such a large size program code. The capacity of the program-storing device can be enlarged to store all sets of program modules for plural image processing functions; however, the result is that the production costs and power consumption of the digital signal processor are generally increased. In addition, when a large number of program modules are simultaneously loaded in the program-storing device, a branching process in a program execution, such as a conditional branching process, may more frequently occur than when a smaller number of program modules are loaded therein, and consequently the throughput of the image processing operation may deteriorate.